The Ten Commandments in the Torah (Exodus 20) are a formulation of the basic precepts (moral principles) of morality. Jews and Christians believe they were revealed by God to Moses, but to understand the content of those precepts does not require the supernatural virtue of faith as such, but are understandable through the natural light of human reason. Let's go over each one:
1. You shall have no other gods besides the Lord your God : As you know by now, it is of the utmost importance to read Scripture in its historical context. Thus, let's keep in mind that the Jews spent years in Egypt, and when Moses came down from Mount Sinai, he found them engaged in revelry; they'd fallen into the worship of the Egyptian god, Apis, who is represented in the Egyptian pantheon as a bull (Ex 32, 1ff). Apis was the god of strength and fertility, that is, power and wealth.
To worship something is to make it the center around which your life revolves. There are many possible things around which a person might center his life. Although very few can be found who actually bow before idols of gold, few can be found who have not made the pursuit of power and wealth their chief purpose in life. No matter what form it may take, violating the first commandment, which is the sin of idolatry, is nothing other than the worship of the self; for the pursuit of power and money as one's principal end is, in the end, a pursuit of the self as center of one's life.
2. You shall not take the Lord's name in vain : This means using God's name frivolously, without reverence, that is, "dragging it through the mud". A person does that when he swears an oath, using God's name: "…so help me God" - thus calling on God as a witness that he is telling the truth -, and then lying. Moreover, swearing is not the same as foul language. Swearing involves using the name of God as a curse; foul language, on the other hand, is just foul language, certainly inconsiderate and a sign of a lack of self-control, but it is much less serious than swearing in the true sense of the word.
3. Keep holy the Sabbath day : For Jews, the Sabbath begins on Friday evening and continues throughout the following Saturday. For Christians, because Christ rose from the dead on Sunday, the Sabbath begins on Saturday evening and continues throughout the following Sunday. For the Jews, the word 'sacred' means 'set apart'. The Sabbath is set apart from all other days as a day of worship and contemplation. This life is about preparing for eternal life, and eternal life is a life of eternal worship and contemplation of God as He is in Himself. This is represented in the 7 day work week, which is an ever recurring microcosm of human life to remind us where we are going. Each day of the week is a work day, but our labour is ordered towards 'rest', which is the Sabbath ( saba is Hebrew for 'seven' and 'oath' by which we enter into covenant). Leisure is a holy activity, and the highest way to leisure is to contemplate, and the highest form of contemplation is to contemplate the highest being, which is God. The very word 'holiday' means holy day . Western culture has lost a sense of this notion of holiday as a holy day, which is why holidays are devoted less to worship than they are to 'shopping'. Consumerism has become the new religion, and the malls have become the new churches.
4. Honour your father and mother, so that you may live long in the land that the Lord is giving you : We have a debt to our parents, a debt that we cannot fully repay. But we are obligated in justice to repay that debt as much as we are able. We do that by honouring them. To honour, for the Jews, meant 'to glorify'. We are called to glorify our parents, who are glorified by our success, because our success reflects back on them. We need to be careful, however, of the way we define success; for it has come to mean a number of different things for different people. Good marks, a well-paying job, material prosperity are "success" relatively speaking, but one can achieve a great deal in this area and turn out to be a moral failure, and that dishonours our parents. Human success has more to do with human integrity, which is a moral achievement. A saint is an example of what it means to be a genuine success.
5. You shall not kill : The human person is created in the image and likeness of God, that is, in the image of "knowledge and love", or "mind and heart". In other words, a human being is like God insofar as he is a person who has the power to think and choose freely. Everything else in creation, i.e., plants, animals, minerals, exists to serve his needs. The human person, on the other hand, was willed into existence by God for his own sake, not as an instrument of the state or an instrument to be used by others (i.e., slavery in all its many forms). We destroy instruments when they are no longer useful (we throw out old computers, televisions, pens, clocks, etc.). But the value of a human being cannot be calculated on the basis of his/her usefulness; to do so is to reduce him or her to a mere instrument to be used. As this utilitarian mentality spreads throughout a culture, we see a corresponding increase in the direct and indirect killing of others (i.e., abortion, infanticide, euthanasia, fraud, the murder of reputations, indifference to the sick, the suffering, the poor, etc.).
6. You shall not commit adultery : The first and immediate community into which we are born is the family, which is the fundamental unit of society, often compared to the cell of the human body. The family begins in marriage, and marriage is holy. It is an institution, that is, an organization that exists for the public welfare. In other words, it is more than a private friendship. Moreover, it was established by God (see Gn 2, 24). Marriage is a complete and mutual self-giving of two, male and female; as such it is a joining of two into a one flesh, one body union. Because this self-giving is total, it is physical, until death, exclusive and undivided, and it is ordered to the generation of new life. The act of sexual union is an expression of this one flesh union; adultery is an act of infidelity to one's marital promises and reduces the sexual act to a lie (one is joining himself to someone who is not his spouse). The precept against adultery includes, within its scope, all sexual activity that is outside of marriage.
7. You shall not steal : A right always corresponds to a duty, and so if you have a duty to raise your children, to protect them, feed them, educate them, etc., then you have a right to the means needed to fulfil those duties. This means you have a right to the property you need to carry out the obligation to rear your children. You have the right to use your talents to create wealth (the goods and services that you produce) and to enter into mutually agreed upon transactions with others (i.e., I will produce this table for you, if you pay me the cost of the materials as well as the cost of the labour). To steal is to take what rightfully belongs to another. If I steal from you, I decide to change the terms of your mutual transactions. For example, you produce something that someone else wants and is willing to pay for; he freely agrees to pay you, let's say, $100 for the product or service. On the table, I see the $100 that you collected from him after the sale. I take it. So I've decided that you are going to produce that good or that service (whatever it was) without any remuneration for your labour. In other words, you are going to work for me, without payment and without your consent. This is a violation of justice.
8. You shall not bear false witness : A liar is a person who cannot be trusted. He is one who brings about a "split" within himself, that is, a division, a degree of disintegration. Lying is an immediate violation of "integrity"; for there is a separation between what is in the liar's word and what is in his mind. Although the truth is in his mind, it is not in his word.
But man has been created in the image and likeness of God, who is absolutely one with His Word, which is why everything comes into existence through the power of His Word: "God said: Let there be light, and there was light…" Hence, I ought to become increasingly one with my words, not divided from them; for the more our word becomes united and filled with the content of the truth that is in us, the more like God we become. The more our word is emptied of that content and is made to express not ourselves but some other falsehood (as happens when we lie), the more unlike God we become.
Lying involves a kind of meditation. Consider a poorly constructed lie: "I couldn't return your urgent call because I was out all weekend, hunting elephants." It is easy to see through such a lie - not much thought has gone into it. A more carefully crafted lie requires more thought and meditation.
Why meditation? The reason is that the mind thinks, but the spirit meditates, and when the liar thinks of the best way to craft his lie, his spirit is open to the best suggestions. But spirit opens upon spirit, not flesh. The spirit of the liar does not open upon God, who is Spirit and Truth, but upon the spirit whom Christ refers to as "the father of lies" (Jn 8, 44), whom Scripture refers to as the most crafty of all God's creatures (Gn 3, 1). The crafty liar engages in a kind of anti-prayer. And the "split" within the self that the liar brings about by lying is a fissure through which the influence of darkness seeps in even further.
As the liar continues to lie - for we are creatures of habit -, he gradually loses himself, and at some point his loss is virtually irretrievable. Soon he will begin to delight in his lies, because through his successes he demonstrates to himself his apparent intellectual superiority over all who have been hoodwinked, every one of whom has become a means to the liar's own ends, puppets within the environment he schemes to construct for himself.
Lying is the very antithesis of prayer, and its effects are equally opposed to those of genuine prayer, such as integration, light, community, and salvation. The only remedy against lying is a commitment that absolutely excludes it, always, everywhere, and in every circumstance.
9 & 10. You shall not covet your neighbor's wife; You shall not covet your neighbor's goods : To covet, as used here, is to have inordinate desire for something or someone. The one who covets is unsatisfied with what he has; or more to the point, with what he is . Everything is subject to the providence of God, and everything that happens is contained within the larger plan of divine providence. This is true even in light of the fact that human beings make free choices. Now all of us have a place within the plan of divine providence. We all have our place in this world, just as an artist assigns a specific place to a particular dab of paint of a particular color. Our place contributes to the splendor of the whole plan of providence fully realised. The problem is we love ourselves too much, and so we must spend the rest of our lives working to decrease that inordinate love of self in order to give greater increase to the love of God and the entire plan of providence. Coveting is a sign that have work to do; it is an indication that we still desire to exceed our natural limitations, to be more than what we are. And that's the root of the problems in this world; we love ourselves too much and others not enough. This commandment calls us to learn to love others as 'another self', to delight in their blessings as if they were our own. The more progress we make along these lines, the happier we become, because the happiness of others eventually becomes our own.
A final thought . There is a reason why the first three commandments have to do with our relationship with God, while the last seven govern our relationship to our neighbours. The reason is that we simply cannot love our neighbour unless we love God first. A right relationship with our neighbor is simply the result of a right relationship with God. If I do not see my neighbour in relation to God, that is, as belonging to Him, it is not long before I begin to love him primarily for the sake of what he does for me. It is only when I see him from God's point of view that I can love him for his own sake, and not for my sake, because God has loved each person into existence for his own sake . Our love of neighbour will merely be an extension or an expression of our love for God. If an atheist truly and genuinely loves his neighbor for his own sake - something I am simply unable to judge with any certainty, one way or another -, then I would have to say that such an "atheist" loves God without explicitly knowing it, just as whoever says, "I love God," but hates his brother, is a liar, "for whoever does not love a brother whom he has seen cannot love God whom he has not seen" (1 Jn 4, 20).